A Genetically Informed Study of Psychosocial Risk Factors for Suicide Attempt/Self-Harm

Suicide is the fourth leading cause of death worldwide among adolescents, and while many young people who engage in self-injury never attempt suicide, for others, it marks a crucial step on the path toward more suicidal behavior. Understanding what leads some young people to move from nonsuicidal self-injury (NSSI) to a suicide attempt (SA) is essential: this transition can mean the difference between behaviors that, while harmful, are not intended to be fatal, and those that can result in physical harm and even death. Because suicide risk emerges from a mix of inherited traits and life experiences, ranging from family history to trauma, and other stressors, one way researchers untangle this puzzle is through twin studies, which can separate the influence of genetics from other factors by comparing identical twins (who share nearly all their genes) to fraternal twins (who share about half). This approach doesn’t always identify specific genes, but it can reveal whether a behavior is partly inherited or mostly shaped by unique life experiences.

With his AFSP grant, Dr. Brian D’Onofrio and colleagues followed nearly 4,000 Swedish twins from age 18 to 24, focusing on those who reported NSSI at 18 and whether they went on to attempt suicide by 24. To assess the role of genetics, the team compared how often both members of identical twin pairs (who share nearly all of their DNA) showed the same patterns of NSSI and suicide attempts, versus fraternal twins (who share only half). If identical twins were more similar to each other than fraternal twins, it suggested a genetic influence. Dr. D’Onofrio found that teens who self-injured at 18 were about five times more likely to later attempt suicide. More than half of the risk for NSSI, and about a third of the risk for suicide attempts, could be traced to inherited factors, with much of the genetic risk for attempts overlapping with that for NSSI. At the same time, individual life experiences unique to each twin played a role in determining who engaged in NSSI in the first place. Together, the findings highlight the need to both monitor young people who self-injure and to address the environmental stressors that can push them toward greater danger.

Citation: Ohlis, A., Li, L., Kuja-Halkola, R., Lundström, S., D'Onofrio, B. M., Hellner, C., Lichtenstein, P., Cederlöf, M., Chang, Z., & Bjureberg, J. (2025). Genetic and environmental aetiologies of the transition from nonsuicidal self-injury to suicide attempt: a longitudinal twin study. Molecular psychiatry, 10.1038/s41380-025-03165-z. Advance online publication. https://doi.org/10.1038/s41380-025-03165-z